Emission system, apparatus, and method

ABSTRACT

An emission reduction apparatus is provided that includes a fuel conversion unit configured to convert a first portion of fuel from a fuel tank into a set of reducing agents that includes hydrogen, an exhaust path configured to convey an exhaust stream containing nitrogen oxides away from an engine, a transport system configured to transport each of a second portion of fuel from the fuel tank, the set of reducing agents, and the hydrogen into the exhaust path such that a mixture is formed, and the catalytic material configured to aid in a conversion of at least a portion of the nitrogen oxides in the exhaust stream of the mixture into nitrogen.

BACKGROUND

1. Technical Field

The invention includes embodiments that relate to an engine exhaustemission reduction system. Embodiments of the invention relate tovehicles, locomotives, generators, and the like. Embodiments of theinvention relate to a method of controlling engine exhaust systememissions.

2. Discussion of Art

Production of emissions from mobile and stationary combustion sourcessuch as locomotives, vehicles, power plants, and the like, contribute toenvironmental pollution. One particular source of such emissions arenitric oxides (NO_(x)), such as NO or NO₂, emissions from vehicles,locomotives, generators, and the like. Environmental legislationrestricts the amount of NO_(x) that can be emitted by vehicles. In orderto comply with this legislation, efforts have been directed at reducingthe amount of NO_(x) emissions.

As such, it may be desirable to have a system that has aspects andfeatures that differ from those that are currently available. Further,it may be desirable to have a method that differs from those methodsthat are currently available.

BRIEF DESCRIPTION OF THE INVENTION

Aspects of the invention provide an apparatus including a fuelconversion unit, an exhaust path configured to convey an exhaust streamthat contains nitrogen oxides away from an engine, a transport system,and a catalytic material positioned within the exhaust path. The fuelconversion unit is configured to convert a first portion of fuel from afuel tank into a set of reducing agents that includes hydrogen. Thetransport system is configured to transport each of a second portion offuel from the fuel tank and the set of reducing agents into the exhaustpath such that a mixture is formed. The mixture comprises the secondportion of fuel, the set of reducing agents, and the exhaust stream. Thecatalytic material is positioned within the exhaust path and configuredto aid in a conversion of at least a portion of the nitrogen oxides inthe mixture into nitrogen. The conversion reduces a quantity of thenitrogen oxides in the exhaust stream.

Aspects of the invention also provide a method that includes convertinga first portion of fuel from a fuel supply to a plurality of firstreductants, and passing the plurality of first reductants into anexhaust stream. The exhaust stream includes a plurality of nitrogenoxides. The method further includes transforming a second portion ofliquid fuel from the fuel supply into a gaseous fuel and passing thefirst reductants, the exhaust stream, and the gaseous fuel over aselective catalytic reduction (SCR) component such that a portion of theplurality of nitrogen oxides is converted into nitrogen.

Aspects of the invention also provide a method that includes acquiring afirst portion of fuel from an engine supply fuel tank, converting thefirst portion of fuel into at least a plurality of reductants, mixingthe plurality of reductants and a quantity of gaseous fuel from a secondportion of fuel from the engine supply fuel tank with an engine exhaustcontaining nitrogen oxides to create a first mixture including theplurality of reductants, the quantity of gaseous fuel, and the engineexhaust. The method further includes catalyzing a chemical reaction inthe first mixture over a selective catalytic reduction (SCR) unit. Thecatalyzed chemical reaction reduces at least a portion of the nitrogenoxides in the first mixture to nitrogen.

Various other features may be apparent from the following detaileddescription and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate at least one preferred embodiment presentlycontemplated for carrying out the invention.

In the drawings:

FIG. 1 is a flowchart depicting an exemplary technique according to anembodiment of the invention.

FIG. 2 is a schematic diagram of an emission reduction scheme accordingto an embodiment of the invention.

FIG. 3 is another schematic diagram of an emission reduction schemeaccording to an embodiment of the invention.

DETAILED DESCRIPTION

The invention includes embodiments that relate to engine emissionreduction systems. The invention includes embodiments that relate to anapparatus for controlling the emissions of an engine. The inventionincludes embodiments that relate to a method of controlling theemissions of an engine.

Embodiments of the invention provide an apparatus including a fuelconversion unit, an exhaust path configured to convey an exhaust streamthat contains nitrogen oxides away from an engine, a transport system,and a catalytic material positioned within the exhaust path. The fuelconversion unit is configured to convert a first portion of fuel from afuel tank into a set of reducing agents that includes hydrogen. Thetransport system is configured to transport each of a second portion offuel from the fuel tank and the set of reducing agents into the exhaustpath such that a mixture is formed. The mixture comprises the secondportion of fuel, the set of reducing agents, and the exhaust stream. Thecatalytic material is positioned within the exhaust path and configuredto aid in a conversion of at least a portion of the nitrogen oxides inthe mixture into nitrogen. The conversion reduces a quantity of thenitrogen oxides in the exhaust stream.

Embodiments of the invention provide a method that includes converting afirst portion of fuel from a fuel supply to a plurality of firstreductants, and passing the plurality of first reductants into anexhaust stream. The exhaust stream includes a plurality of nitrogenoxides. The method further includes transforming a second portion ofliquid fuel from the fuel supply into a gaseous fuel and passing thefirst reductants, the exhaust stream, and the gaseous fuel over aselective catalytic reduction (SCR) component such that a portion of theplurality of nitrogen oxides is converted into nitrogen.

Embodiments of the invention provide a method that includes acquiring afirst portion of fuel from an engine supply fuel tank, converting thefirst portion of fuel into at least a plurality of reductants, mixingthe plurality of reductants and a quantity of gaseous fuel from a secondportion of fuel from the engine supply fuel tank with an engine exhaustcontaining nitrogen oxides to create a first mixture including theplurality of reductants, the quantity of gaseous fuel, and the engineexhaust. The method further includes catalyzing a chemical reaction inthe first mixture over a selective catalytic reduction (SCR) unit. Thecatalyzed chemical reaction reduces at least a portion of the nitrogenoxides in the first mixture to nitrogen.

Embodiments of the invention provide a method that includes acquiring afirst portion of fuel from an engine supply fuel tank, converting thefirst portion of fuel into at least a plurality of reductants, mixingthe plurality of reductants and a gaseous second portion of fuel fromthe engine supply fuel tank with an engine exhaust containing nitrogenoxides to create a first mixture including the plurality of reductants,the second portion of gaseous fuel, and the engine exhaust. The methodfurther includes catalyzing a chemical reaction in the first mixtureover a selective catalytic reduction (SCR) unit. The catalyzed chemicalreaction reduces at least a portion of the nitrogen oxides in the firstmixture to nitrogen.

Referring to FIG. 1, a technique 100 for reducing noxious emissions froman engine is depicted according to an embodiment of the invention.According to the embodiment of FIG. 1, a technique 100 for reducingnitrogen oxide (NO_(x)) emissions from an engine is shown. At BLOCK 102,a first portion of fuel from an engine (e.g., an internal combustionengine such as a spark or compression ignition engine) fuel supply isconverted into at least a set of first reductants. A second portion offuel from the same engine fuel supply is transformed into a gaseous fuelat BLOCK 104. The set of first reductants of BLOCK 102 and the gaseousfuel of BLOCK 104 are allowed to mix with an exhaust stream of theengine to create a mixture at BLOCK 106. At BLOCK 108, the mixture isallowed to pass over or through a selective catalytic reduction (SCR)unit to reduce NO_(x) emissions. That is, as the mixture passes over theSCR unit, a chemical reaction takes place that reduces the quantity ofNO_(x) in the exhaust stream. As such, NO_(x) emissions are reduced. Anexemplary chemical reaction of a NO_(x) emission reduction may berepresented by:

NO_(x)+O₂+organic reductant

N₂+CO₂+H₂O   (Eqn. 1).

Technique 100 can be employed using a wide variety of engines, not justcombustion engines. For example, embodiments of the inventioneffectively reduce engine NO_(x) emissions of vehicles, locomotives,generators, gas turbines of power plants, or the like. That is,embodiments of the invention are effective for reducing emissions fromany exhaust source containing NO_(x). As shown in the flowchart of FIG.1, two separate fuel sources are not required to reduce NO_(x)emissions. That is, NO_(x) emissions may be reduced using fuel from thesame supply that powers the engine.

SCR catalysts are those catalyst materials that enable the chemicalreduction of NO_(x) species to less harmful constituents such asnitrogen (i.e., N₂). Many of the SCR catalyst materials that promotereduction of NO_(x) species via reaction with an exhaust stream andreductants may be suitable for use in embodiments of the inventiondescribed herein. For example, silver on an Alumina support that iscoated on a monolith support structure may be used. In particular, 3.0%silver on Mesoporous Alumina that is coated on a monolith core has beenfound to be particularly effective in embodiments described herein.

A schematic block diagram embodying technique 100 of FIG. 1 is depictedin FIG. 2. Although fuel described in embodiments herein may comprisediesel fuels, it is contemplated that embodiments of the invention may,in the alternative, use other fuels such as jet-fuel, fuel oil, andbio-fuels such as bio-diesel. In one embodiment, the fuel compositioncan be bio-diesel or another bio-fuel. In other embodiments, the fuelcomposition includes synthetic fuels with compositions similar toconventional fuels. Further non-limiting examples include gasoline andother fuels obtained by petroleum refining. In some embodiments, thisincludes fuels from distillate fuels, diesel fuel oil, light fuel oiland the like. As shown in FIG. 2, a first portion of diesel fuel 120from an engine diesel fuel supply 122 is allowed to pass through a fuelconversion unit (e.g., a diesel conversion unit (DCU)) 124 where it isconverted into a set or plurality of reductants such as hydrogen. TheDCU 124 may contain an auto thermal cracking material, a catalyticpartial oxidation material, or the like to enable such a conversion.With regard to auto thermal cracking materials, a cracking catalyst isemployed. The term “cracking catalyst” refers to those catalysts thatenable reactions that convert a hydrocarbon material having acomparatively high molecular weight (e.g., diesel or ultra low sulfurdiesel) into one or more hydrocarbon species having lower molecularweights. With regard to the DCU 124, the cracking catalyst materialenables conversion of the primary hydrocarbon into at least onesecondary hydrocarbon having a lower molecular weight than the primaryhydrocarbon. In addition, the cracking component conveniently allows forthe production of reductant species from the very fuel 122 powering theengine 123. The cracking catalyst can also convert the fuel from thediesel fuel supply 122 into carbon monoxide, carbon dioxide, andreductants or co-reductants such as hydrogen. In one embodiment, thecracking catalyst material comprises a zeolite. Zeolites may be favoredfor their effectiveness in enabling cracking of heavy hydrocarbons.Zeolite crystals, found in such cracking catalysts, have a regularnetwork of very small diameter pores, the size and nature of which canbe controlled by controlling the chemistry and processing of thezeolite. Zeolites include silicon or aluminum atoms tetrahedrallysurrounded by four oxygen atoms. A tetrahedron containing silicon isneutral in charge, while each tetrahedron containing aluminum has a netcharge of −1, which must be balanced by a positive ion such as a proton.Protons that balance the negative charge of aluminum tetrahedral havestrong acidity, which is known to catalyze cracking reactions. Thus, thecatalyzing properties of the zeolite, in addition to being controlled bycontrolling pore size, may be further controlled by proper selection ofa “silicon to aluminum ratio” of the zeolite, (i.e., the relativeamounts of aluminum and silicon in the zeolite).

In embodiments of the invention, the DCU 124 may include a catalyticpartial oxidation (CPO) material. CPO materials are capable of enablingthe conversion of hydrocarbon species, such as the primary hydrocarbon(e.g., the first portion of diesel fuel 120), into a syngas (a mixtureof hydrogen and carbon monoxide). This syngas, as will be described ingreater detail below, can be used to further increase the rate of NO_(x)reduction. CPO materials have catalyst-endowed functional capabilities.Further, CPO materials also help to minimize the degradation of crackingcatalysts resulting from coke build-up. Coke build-up occurs during avariety of processes, such as fluidized catalytic cracking (FCC). Assuch, during the cracking of hydrocarbons, coke often builds up on thesurface of the cracking catalysts. By employing a CPO material, cokebuild-up on the surface of the cracking catalyst material may beremoved, thereby retaining active sites for cracking appreciably longerthan would be available if the CPO material were not present. Further,since a catalytic partial oxidation reaction is an exothermic reactionwhile cracking is an endothermic reaction, the heat generated at acatalytic partial oxidation site facilitates the endothermic crackingreaction in a neighboring cracking site while also facilitating theoxidation of coke that may be present in the DCU 124.

The CPO material generally comprises one or more noble metals thatperform the catalytic partial oxidation function. In particularembodiments, the CPO material comprises one or more “platinum group”metal components. As used herein, the term “platinum group” metal meansrhodium, platinum, iridium, palladium, osmium, ruthenium, or mixtures ofany of these. Exemplary platinum group metal components are rhodium,platinum, and optionally, iridium. The platinum-group metal is presentin the multifunctional catalyst in an amount greater than about 0.1weight percent, such as in a range from about 0.1 weight percent toabout 5 weight percent. A particular exemplary composition for the CPOmaterial is 0.5% Pt-0.5% Rh-0.25% Ir (percentages based on total loadingby weight of multi-functional catalyst). In alternative embodiments, theplatinum-group metal is present in the multi-functional catalyst in anamount of about 1 weight percent. The platinum group metal componentsoptionally may be supplemented with one or more base metals and oxidesof the metals, including, for example, base metals of Group VIIIB, GroupIB, Group VB and Group VIB of the Periodic Table of Elements. Exemplarybase metals include cerium, iron, cobalt, nickel, copper, vanadium, andchromium. In some embodiments, the CPO material is disposed on thecracking catalyst.

Still referring to the embodiment of FIG. 2, once created by the DCU124, the reductants, including any hydrogen, in the DCU output 126 areallowed to pass into an engine exhaust path 128. As a result, the DCUoutput 126 mixes with the engine exhaust stream 130, which contains aplurality of nitrogen oxides (NO_(x)). A second portion of diesel fuel132 passes into the engine exhaust path 128 by, for example, anatomization or spray method. Upon entering the exhaust path 128, theheat from the exhaust stream 130 transforms the second portion of dieselfuel 132 into gaseous diesel fuel. The constituents described above,that is, the DCU output 126 and the second portion of diesel fuel 132,may be conveyed into the exhaust path 128 via a transport system 134comprising containment tubes, hoses, or the like.

As a consequence of passing the set of reductants in the DCU output 126,which may include hydrogen, along with the second portion of diesel fuel132 from the diesel fuel supply 122 into the exhaust stream 130, amixture 136 is created. This mixture 136 is allowed to pass over or intothe SCR unit 138 located within the exhaust path 128. The SCR unit 138enables a chemical reaction to take place, where the hydrocarbonspresent in the second portion of diesel fuel 132 and the hydrocarbonspresent (if any) in the DCU output 126 reduce at least a portion of theNO_(x) in the exhaust stream 130 to at least nitrogen (N₂). As such, theamount of NO_(x) in the engine emissions 140 is reduced. Further, any H₂present in the DCU output 126 will increase the rate of NO_(x) reductionover the SCR unit 138 at given temperatures. In one embodiment, whichwill be more fully described through example with respect to FIG. 3, thequantity of H₂ produced by the DCU 124 may be manipulated by allowingoxygen 142 into the DCU 124 environment. The intake of such oxygen maybe controlled by a control component 144, which will also be more fullydescribed with respect to FIG. 3.

The second portion of fuel 132 and the set of reducing agents, whichincludes the hydrogen, in the DCU output 126 all act as reducing agentsover the catalytic material for the conversion of nitrogen oxides. Theproportions of each of these reducing agents can be adjusted to optimizethe conversion of nitrogen oxides. Examples of the manner in which suchoptimizations may occur will be more fully described below with respectto FIG. 3

Referring now to FIG. 3, a schematic diagram according to an embodimentof the invention is shown, which illustrates NO_(x) reduction in engineemission in a “cool” environment. Due to the nature of the chemicalreaction that occurs that reduces the amount of NO_(x) in the exhauststream 130, the rate at which the reaction occurs is often slowed as thetemperature of the exhaust stream 130 is reduced. However, this rate canbe increased if the mixture 136 also contains hydrogen (H₂). To exploitthe effects of H₂ as a reductant or co-reductant, oxygen 142 and thefirst portion of fuel 120 is allowed to pass through the fuel conversionunit 124 having a CPO material (not shown) therein. The oxygen could,for example, come from an air intake on the fuel conversion unit 124.That is, in one embodiment, ambient air may be brought into the fuelconversion unit 124 to provide an “oxygen rich” environment. Due to the“oxygen rich” fuel conversion unit 124 environment (i.e., an environmentthat includes the first portion of fuel 120 and oxygen 142), a chemicalreaction occurs that results in a quantity of hydrogen (H₂), areductant, being present among the set of reductants in the fuelconversion unit output 126. As such, by manipulating the amount ofoxygen allowed to pass into the fuel conversion unit 124, the productionof H₂ can be controlled. In addition to manipulating the amount ofoxygen that enters the fuel conversion unit 124 to control H₂production, the temperature of the fuel conversion unit 124 may also bemanipulated to increase or decrease the amount of hydrogen that will bepresent among the set of reductants in the fuel conversion unit output126. Once created, the reductants, along with the H₂, are then allowedto pass into the exhaust stream 130 with the second portion of fuel 132.As a consequence, the mixture 136 now includes H₂, which can increasethe rate of NO_(x) reduction over the SCR unit 138. Though describedabove in terms of increasing the rate of NO_(x) reduction in a “cool”exhaust stream 130, it will be appreciated by one skilled in the artthat the H₂ may also increase the reduction rate in a “warm”environment.

Further, it is contemplated that a water gas shift (WGS) catalyst 150could be employed to further increase the quantity of H₂ entering intothe mixture 136. For example, still referring to FIG. 3, the system canbe configured such that the fuel conversion unit output 126 is allowedto pass over or through a sulfur tolerate water gas shift catalyst 150(shown in phantom). The reductants found in the fuel conversion unitoutput 126 generally include H₂, CO, and light hydrocarbons. The COfound in the fuel conversion unit output 126 can be converted intoadditional H₂ by passing it and the other output reductants 126 over theWGS catalyst 150. Steam in the catalyst, either brought in with thereductants or injected from another steam source 153 (shown in phantom),reacts with the CO to produce H₂ as represented by the followingequation:

CO+H2O

H2+CO2   (Eqn. 2).

As such, the WGS output 152 will have a greater quantity of H₂ than thefuel conversion unit output 126. That is, the WGS output 152 willinclude H₂ from the fuel conversion unit output 126 and H₂ producedduring the WGS reaction over the WGS catalyst 150. Consequently, theNO_(x) reduction of the SCR unit 138 will increase. As discussed above,it is contemplated that the steam brought in for the reaction over theWGS catalyst 150 may come from an outside steam source 153. Since atypical WGS reaction occurs within a given temperature range (e.g.,250-450° C.), the steam brought in from the outside steam source 153 canalso cool the fuel conversion unit output 126 to within the WGS reactiontemperature range. For fuels containing sulfur, it is preferable thatthe WGS catalysts 150 is commercially available sulfur tolerate WGScatalyst. For bio-fuels that do not contain sulfur, an active noblemetal WGS catalysts can be used to reduce the size of the WGS catalystbed.

As shown in FIG. 3, it is contemplated that a control component 144 suchas a switch or other control circuit can provide control capabilities tothe system. Such control capabilities can include the manipulation ofthe reducing agent ratios relative to one another and/or themanipulation of the rate the reducing and/or co-reducing agents arecreated. For example, a control component 144 may be employed to allowor not allow quantities of oxygen 142 to pass into the fuel conversionunit 124. If the exhaust stream 130 were cool, whether due toenvironmental reasons or other conditions, the control component 144could be “turned on” to create an “oxygen rich” environment in the fuelconversion unit 124, thus enabling a CPO material in the fuel conversionunit 124 to create at least hydrogen. As such, the rate of NO_(x)reduction over the SCR unit 138 can be increased. On the other hand, ifthe exhaust stream 130 were “warm,” the control component 144 could beturned off, thus not allowing oxygen 142, or extra oxygen, to enter thefuel conversion unit 124 environment. As a result, the cracking materialof the fuel conversion unit 124 converts the first portion of fuel 120into a set of reductants rich with hydrocarbons. In such an embodiment,the mixture 136 is a combination of the set of reductants rich withhydrocarbons that comprises the fuel conversion unit output 126, theexhaust stream 130, and the hydrocarbons of the gaseous fuel (i.e., thesecond portion of fuel 132). Using the plurality of hydrocarbons, theSCR unit 138 aids in the reduction of the quantity of NO_(x) in theemissions 140.

It is further contemplated that the control component 144 of FIG. 3could be controlled in such a manner to fine tune the amount of oxygen142 allowed to pass into the fuel conversion unit 124 environment, thusmaximizing the NO_(x) reduction rates in a variety of environments. Thatis, for example, by repetitively switching the control component 144 atdifferent rates, the quantity of H₂ and hydrocarbons in the fuelconversion unit output 126 can be manipulated. As such, the rate atwhich the hydrogen and reducing agents are created can also bemanipulated. The activation or deactivation of the control component 144could also be employed to by-pass the fuel conversion unit 124.Accordingly, hydrocarbon reducing agents or H₂ would not be created bythe fuel conversion unit 124. For example, if it is determined that H₂is not needed to increase the rate of NO_(x) reduction because theexhaust stream 130 is “warm,” and/or it is determined that excesshydrocarbons created with the cracking material are not needed, thecontrol component 144 could be activated (e.g., “turned off”) such thatthe fuel conversion unit 124 is by-passed or not used.

Still referring to FIG. 3, it is also contemplated that a “stateconversion unit” 154 could be employed to transform the second portionof fuel 132 from the fuel supply 122 into gaseous fuel. For example,rather than relying on an atomizer, or the like, and the heat of anexhaust stream 130, as described with respect to FIG. 2, a heatingelement 154 could be employed to transform the second portion of fuel132 into gaseous fuel. As such, the gaseous fuel output 156 and the fuelconversion unit output 126 could then be allowed to pass into theexhaust stream 130 via the transport system 134. Further control may beenabled through the utilization of the contemplated controller 158 orthe like. Such a controller could be used to manipulate the quantity offuel allowed to enter the exhaust path 128 and the fuel conversion unit124. As such, the degree of NO_(x) reduction may be controlled.

A technical contribution for the disclosed method and apparatus is thatit provides for a controller implemented control of NO_(x) emissions.

The invention has been described in terms of the preferred embodiment,and it is recognized that equivalents, alternatives, and modifications,aside from those expressly stated, are possible and within the scope ofthe appending claims.

1. An apparatus comprising: a fuel conversion unit configured to converta first portion of fuel from a fuel tank into a set of reducing agents,wherein the set of reducing agents comprise hydrogen; an exhaust pathconfigured to convey an exhaust stream away from an engine, wherein theexhaust stream comprises nitrogen oxides; a transport system configuredto transport each of a second portion of fuel from the fuel tank and theset of reducing agents into the exhaust path such that a mixture isformed, wherein the mixture comprises the second portion of fuel, theset of reducing agents, and the exhaust stream; and a catalytic materialpositioned within the exhaust path and configured to aid in a conversionof at least a portion of the nitrogen oxides in the mixture intonitrogen, wherein the conversion reduces a quantity of the nitrogenoxides in the exhaust stream.
 2. The emission reduction apparatus ofclaim 1 further comprising a control component configured to adjust arate at which the fuel conversion unit converts the first portion offuel into the set of reducing agents such that a quantity of thehydrogen produced is manipulated.
 3. The emission reduction apparatus ofclaim 1 wherein the first and second portion of fuel is a first andsecond portion of diesel fuel, respectively.
 4. The emission reductionapparatus of claim 1 further comprising a state conversion unitconfigured to transform the second portion of fuel into a gas before thesecond portion of fuel enters into the exhaust stream.
 5. The emissionreduction apparatus of claim 1 further comprising an oxygen intakeconfigured to transport oxygen into the fuel conversion unit to initiatecatalytic partial oxidation to convert the first portion of fuel fromthe fuel tank into the set of reducing agents, wherein the hydrogen inthe mixture increases a rate of the conversion of the mixture over thecatalytic material within the exhaust path.
 6. The emission reductionapparatus of claim 1 wherein the fuel conversion unit is configured toinitiate auto-thermal cracking to convert the first portion of fuel fromthe fuel tank into the set of reducing agents, wherein the set ofreducing agents further comprises secondary hydrocarbons and carbonmonoxide.
 7. The emission reduction apparatus of claim 6 wherein thefuel conversion unit is further configured to convert at least a portionof the secondary hydrocarbons into hydrogen such that a rate of theconversion of the mixture is increased, wherein the conversion of themixture is aided by the catalytic material.
 8. The emission reductionapparatus of claim 1 further comprising a water gas shift catalyst toconvert a portion of the reducing agents from the fuel conversion unitinto additional hydrogen.
 9. A method comprising: converting a firstportion of fuel from a fuel supply to a plurality of first reductants;passing the plurality of first reductants into an exhaust stream,wherein the exhaust stream comprises a plurality of nitrogen oxides;transforming a second portion of liquid fuel from the fuel supply into agaseous fuel; and passing the plurality of first reductants, the exhauststream, and the gaseous fuel over a selective catalytic reduction (SCR)component such that a portion of the plurality of nitrogen oxides isconverted into nitrogen.
 10. The method of claim 9 wherein the firstportion of fuel from the fuel supply is converted to the plurality offirst reductants by passing the first portion from the fuel supply overa fuel conversion unit.
 11. The method of claim 10 further comprising:passing a quantity of oxygen over the fuel conversion unit such thathydrogen is produced; regulating the quantity of oxygen passing over thefuel conversion unit such that the production of the hydrogen isregulated; and regulating the first portion of fuel from the fuel supplypassing through the fuel conversion unit such that the production of thehydrogen is regulated.
 12. The method of claim 9 further comprisingregulating the transformation of the second portion of liquid fuel fromthe fuel supply into the gaseous fuel such that the conversion of theplurality of nitrogen oxides into nitrogen is regulated.
 13. The methodof claim 9 further comprising ceasing the conversion of the firstportion of fuel to the plurality of first reductants based on one of anexhaust stream temperature and a nitrogen oxide concentration in theexhaust stream.
 14. The method of claim 9 wherein converting the firstportion of fuel from the fuel supply to the plurality of firstreductants comprises implementing at least one of auto thermal crackingand catalytic partial oxidation.
 15. The method of claim 9 wherein thefirst and second portion of fuel is diesel fuel.
 16. The method of claim9 further comprising: converting a portion of the first portion of fuelinto hydrogen; and passing the hydrogen over the SCR component toincrease a reaction rate at which the portion of the plurality ofnitrogen oxides is converted into the nitrogen.
 17. The method of claim16 further comprising increasing a temperature of a catalyst in a fuelconversion unit to increase production of the hydrogen.
 18. A methodcomprising: acquiring a first portion of fuel from an engine supply fueltank; converting the first portion of fuel into at least a plurality ofreductants; mixing the plurality of reductants and a quantity of gaseousfuel from a second portion of fuel from the engine supply fuel tank withan engine exhaust containing nitrogen oxides to create a first mixturecomprising the plurality of reductants, the quantity of gaseous fuel,and the engine exhaust; and catalyzing a chemical reaction in the firstmixture over a selective catalytic reduction (SCR) unit, wherein thechemical reaction reduces at least a portion of the nitrogen oxides inthe first mixture to nitrogen.
 19. The method of claim 18 wherein the atleast a plurality of reductants comprises a quantity of hydrogen, andwherein the quantity of hydrogen increases a rate at which the nitrogenoxides reduce over the SCR unit.
 20. The method of claim 19 furthercomprising at least one of: adjusting the quantity of hydrogen producedduring the conversion of the first portion of the fuel such that a rateof the reduction of the at least a portion of the nitrogen oxides in thefirst mixture to the nitrogen is regulated; and adjusting the quantityof gaseous fuel mixed with the plurality of reductants and the exhauststream such that the rate of the reduction of the at least a portion ofthe nitrogen oxides in the first mixture to the nitrogen is regulated.21. The method of claim 18 wherein the engine supply fuel tank holdsfuel that contains diesel.
 22. The method of claim 18 wherein theplurality of reductants comprises secondary hydrocarbons.
 23. The methodof claim 22 further comprising: converting the secondary hydrocarbons tohydrogen; and mixing the hydrogen with the first mixture to increase arate at which the nitrogen oxides reduce over the SCR unit.